Field of the Invention
The present invention relates to the preparation of potatoes, and more specifically, the preparation of intermediate-moisture potatoes that may be stored on the shelf for extensive time periods without the need for refrigeration.
It is well known in the prior art that potatoes may be dehydrated, but extensive problems have resulted in producing a final product that has high quality from consumer considerations. Flavor loss from the processing steps has caused lower quality than is desired. Additionally, storage of the dehydrated product may necessitate specific conditions such as refrigeration, including freezing. Upon rehydration, non-uniform water absorption in the product may result which also lowers product quality.
A recent development in the food industry is the emphasis on intermediate-moisture foods which have the ability of being stored and marketed in a substantially non-refrigerated condition. These foods were designed to avoid the need to be packaged in a hermetically sealed container and commercially sterilized or maintained in a frozen or refrigerated state throughout the period of distribution and storage by the consumer.
The intermediate-moisture foods are based on the principle of reducing the availability of water in the food for microbial growth. The availability of water for germination and microbial growth is closely related to its relative vapor pressure, commonly designated as water activity. It was found that the use of a wide variety of water-soluble solutes, or osmotic agents, has the effect of depressing the water activity of the foods to levels at which most bacteria will not grow.
The water activity of a food is defined as the partial pressure of water in the food divided by the saturation pressure of water at the temperature of the food. The water activity can be determined by placing a sample in a container which is then sealed, and after equilibrium is reached, determining the relative humidity above the sample. Most intermediate-moisture products have between 10 to 40% moisture, and a water activity between 0.65 and 0.9.